Systems and Methods for Full-Duplex Signal Shaping

ABSTRACT

The current subject matter relates to a system and a method for processing signals. The system can include a transmitting antenna for transmitting a signal over a plurality of wireless spectrum fragments, a receiving antenna for receiving a signal from the plurality of wireless spectrum fragments, and a signal processing layer in communication with the transmitting and receiving antennas for simultaneously causing reception of the received signal and transmission of the transmitted signal. The signal processing layer can include an interference cancellation component for removing a first portion of interference from the received signal and a filtering component for removing a second portion of the interference from the received signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication No. 61/596,628 to Hong et al., filed Feb. 8, 2012, and isentitled “Enabling Algorithms and RF Circuitry for Full-duplexCommunication Over Arbitrary Spectrum Fragments,” and incorporates itsdisclosure herein by reference in its entirety.

TECHNICAL FIELD

In some implementations, the subject matter described herein relates towireless communications processing, and in particular, to full-duplexsignal shaping in communication systems.

BACKGROUND

Communication systems are essential to everyday life as they providenecessary connections between parties, devices, networks, and systemsallowing vital exchange of information. Communication systems come indifferent varieties and can include optical communication systems, radiocommunication systems, power communication systems, duplex communicationsystems, and others. A duplex communication system is a point-to-pointsystem that connects two parties or devices communicating with oneanother in both directions. An example of a duplex device is atelephone, which includes a speaker and a microphone and can be used toconduct a telephone call. The parties at both ends of the call can speakat the same time, where the speakers of the parties' telephonesreproduce the sounds transmitted by the microphones of the other partytelephone. Thus, duplex communication systems provide a “two-way street”between connected parties, as opposed to a “one-way street” in simplexcommunication systems where one device transmits and the other onelistens (e.g., broadcast radio and television, garage door openers, babymonitors, wireless microphones, radio-controlled models, surveillancecameras, etc.).

A full-duplex (“FDX”), or sometimes double-duplex system, allowscommunication in both directions, and, unlike half-duplex allows this tohappen simultaneously. Land-line telephone networks are full-duplex,since they allow both callers to speak and be heard at the same time.

However, conventional full-duplex communication systems suffer from avariety of drawbacks, including an inability to simultaneously receiveand transmit signals without reduction or elimination of interferenceand/or receiver saturation. These drawbacks can significantly reducecommunication system's throughput acid ability to provide fast andreliable service to consumers.

SUMMARY

In some implementations, the current subject matter relates to a systemfor processing signals. The system can include a transmitting antennafor transmitting a signal over a plurality of wireless spectrumfragments, a receiving antenna for receiving a signal from the pluralityof wireless spectrum fragments, and a signal processing layer incommunication with the transmitting and receiving antennas forsimultaneously causing reception of the received signal and transmissionof the transmitted signal. The signal processing layer can include aninterference cancellation component for removing a first portion ofinterference from the received signal and a filtering component forremoving a second portion of the interference from the received signal.The interference can be caused by the transmitted signal and affectingthe received signal.

In some implementations, the current subject matter can include one ormore of the following optional features. The portion of interference tobe removed by the interference cancellation component can equal to apredetermined amount of power to be removed from the received signal.The predetermined amount of power can be determined based on at leastone of the following: dynamic range of at least one of the received andtransmitted signals, and a range of expected signal strength, thedynamic range of the received signal is determined based on a ratio ofpowers of a strongest received signal and a weakest received signal, thedynamic range of the transmitted signal is determined based on a ratioof powers of a strongest transmitted signal and a weakest transmittedsignal, and the range of expected signal strength is determined based ona distance separating the transmitting antenna and a receiving antenna.The interference cancellation component can include abalanced-unbalanced transformer component for subtracting thepredetermined amount of power from the received signal. In someimplementations, the interference cancellation component can include atleast one passive electronic component.

In some implementations,the filtering component can chide a receivercircuitry for performing at least one of the following operations:sampling of the received signal, down-converting the sampled receivedsignal into a narrowband stream, and filtering the down-converted signalto remove the second portion of the interference. The filteringcomponent can include a transmitter circuitry fir performing at leastone of the following operations: up-converting of the transmitted signaland filtering the up-converted signal to prevent aliasing of thetransmitted signal with at least another signal. The filtering componentcan include a plurality of filters arranged in a sequence for performingsampling and filtering of the received signal processed by theinterference cancellation component to remove the second portion of theinterference. The plurality of filters can include at least oneprogrammable filter, which includes at least one of the following; afinite impulse response filter, infinite impulse response filter, and aresampling filter. In some implementations,the filtering component canperform mapping of at least one signal received from at least onecommunication protocol layer to at least one frequency fragment in awireless frequency band for transmission by the transmitting antenna.

The received signal and the transmitted signal can be in the wirelessfrequency band.

In some implementations, the current subject matter relates to a methodfor processing of signals using the above-referenced system. The methodcan include removing, using an interface cancellation component of thesignal processing layer, a first portion of interference from thereceived signal and removing, using a filtering component of the signalprocessing layer, a second portion of the interference from the receivedsignal.

The details of one or more variations of the subject matter describedherein are set forth in the accompanying drawings and the descriptionbelow. Other features and advantages of the subject matter describedherein will be apparent from the description and drawings, and from theclaims.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, show certain aspects of the subject matterdisclosed herein and, together with the description, help explain someof the principles associate(with the disclosed implementations. In thedrawings,

FIG. 1 illustrates an exemplary radio, such as a base station or anaccess point, according to some implementations of the current subjectmatter;

FIG. 2 illustrates an exemplary radio, such as a userequipment,according to some implementations of the current subjectmatter;

FIG. 3 illustrates an exemplary full-duplex communication system havinga signal shaping layer, according to some implementations of the currentsubject matter;

FIG. 4 illustrates an exemplary full-duplex signal shaping system,according to some implementations of the current subject matter;

FIG. 5 illustrates exemplary radio devices configured to operate indifferent fragments of a wireless spectrum; and

FIG. 6 illustrates an exemplary method for full-duplex signal shaping,according to some implementations of the current subject matter.

DETAILED DESCRIPTION

To address the above noted deficiencies of conventional communicationsystems, in some implementations, the current subject matter relates toa system for processing signals and, in particular, to a full-duplexsignal shaping system. The system can include a transmitting antenna fortransmitting a signal over a plurality of wireless spectrum fragments, areceiving antenna for receiving a signal from the plurality of wirelessspectrum fragments, and a signal processing layer in communication withthe transmitting and receiving antennas for simultaneously causingreception of the received signal and transmission of the transmittedsignal. The signal processing layer can include an interferencecancellation component tier eliminating a portion of interference fromthe received signal. The interference can be caused by the transmittedsignal and affect the received signal. The signal processing layer canalso include a filtering component for programmatically removingremaining interference from the received signal. Thus, the currentsubject matter system is capable of simultaneous transmission andreception of signals substantially without interference affecting thetransmitting and/or receiving antennas.

In conventional communications systems, simultaneous transmission andreception, even over different bands, cannot typically be achievedwithout some form of ancillary processing because the transmitted signalcan be orders of magnitude stronger than the received signal.Specifically, if a radio has two antennas, one for transmit and one forreceive, the transmit antenna signal can interfere and cause receiversaturation. For example, when the analog-to-digital converter (“ADC”)samples the analog signal on the receive antenna, the ADC can converteach sample into a number corresponding to a voltage level. The value ofeach sampled point can be represented by a fixed length variable, whichcan have a size determined by the resolution, or dynamic range, of theADC. If for example, the ADC has a resolution of n bits (e.g., n=12),thee the ADC can only hold values from 0 to 2^((n-1)). As such, theself-interference can typically be billions of times stronger than thereceived signal. Indeed, in the example case of WiFi™, theself-interference can be nearly 60-70 dB stronger than the receivedsignal. The dynamic range of an ADC is typically not large enough toacquire the received signal in the face of such large self-interference,so the receiver can become saturated and the received signal iseffectively “lost” in quantization. In addition, this saturation canoccur even, when the transmitted signal are on a different spectrumfragment than received signal.

In some implementations, the subject matter system can enable afull-duplex communication over arbitrary spectrum fragments, so thatsimultaneous transmission and reception over different frequencychannels can occur over the different frequency channels (which canarbitrary e.g., not specified in advance and which can vary in time). Insome implementations, the subject matter system can utilize acombination of mechanisms (e.g., analog circuitry and digital processes)to achieve full-duplex communication over a plurality of spectrumfragments (e.g., arbitrary portions of the spectrum fragments). Toprevent receiver saturation, the current subject matter system cancancel the self-interference (e.g., between the transmission and thereceived), rather than filter the self-interference. In other words, theself-interference signal can be subtracted from the received signal, sothat the self-interference is eliminated and, as such, receiversaturation may not occur.

In some implementations, the analog circuitry component the currentsubject matter system can provide sufficient cancellation to ensure thatthe receiver saturation does not take place. Moreover, the analogcircuitry component of the current subject matter system can beconfigured so that it cannot leak any interference to adjacent spectrumfragments. For example, the analog circuitry can provide analogcancellation based on the use of passive components and/or the use of abalanced-unbalanced transformer (“balun”) as a subtractor, as discussedbelow.

Active cancellation components can often cause interference leakagebecause these components can face power saturation and clip the signal.Hence, to avoid interference leakage, the current subject matter systemcan use passive components to avoid introducing distortion. Whileprogrammable passive attenuators are available off the shelf, passivedelay lines are typically not. Nevertheless, because the activecancellation only needs, in some implementations, 20-25 dB ofcancellation, the analog circuitry for analog cancellation can include apassive programmable attenuator and a simple wire whose length isstatically matched roughly to the over-the-air delay for the transmittedsignal.

Furthermore,instead of using the balun as a signal inversion technique(which typically introduces about a 3 dB power loss), the analogcancellation can implement a subtractor circuit some implementations.For example, a balun in a typical operational configuration takes aninput signal on the unbalanced tap and produces two output signals thatare inverses of each other on the balanced taps. The same operation canbe modeled in reverse as taking two inputs on the balanced side andproducing the subtraction of the input signals as the signal on theunbalanced side. Hence, if the two inputs of the balun are exactreplicas of each other, the output of the balun will be a zero signal.

Self-interference cancellation can thus prevent the receiver ADC fromsaturating, but by itself, self-interference cancellation may not besufficient to fully cancel out the interference between bands. But nowwith the ADC dynamic range no longer saturated, the subject matterdescribed herein can provide systems which utilize programmable digitalfilters (also referred to as a filter engine) to digitally remove anyremaining self-interference from the received signal. The filter enginecan be configured to ensure that the transmitted or received, signalsare shaped according to, for example, a higher-layer specificationdefining which spectrum fragments to use for transmission/reception. Atthe receiver side, this can include converting the sampled widebandsignal into narrowband streams by down converting and filtering toremove adjacent band interference. The reverse functionality is neededat the transmitter side, narrowband baseband streams have to be upconverted and filtered to prevent aliasing.

In some implementations, a system can be provided which includes aself-interference cancellation circuitry block and a filtering engine.This combination can, in some implementations, enable full-duplex signalshaping.

In some implementations, there can be provided a system for full-duplexsignal shaping by allowing radios to transmit and receive simultaneouslyon different, arbitrary channels that are not specified in advance. Thiscan be used in a wide range of radios (e.g., mobile cellular devices,IEEE 802.22 white space devices. IEEE 802.15.4 sensor network nodes) andenable them to either replace several discrete components, such asduplexers, and operate on different channels of varying widths atdifferent times.

In some implementations, there can be provided a centralized accesspoints (e.g., cellular base station or WiFi™ access point) configured toprovide full-duplex signal shaping, which would allow an access point toutilize varying amounts of spectrum to support different users. Also,because the ability to simultaneously transmit and receive acrossdifferent fragments decouples the use of each fragment, different userscan run different applications with varying latency requirements and notsubstantially affect one another.

In some implementations, full-duplex signal shaping can enhance outingprotocols (e.g., wireless mesh networks). Full-duplex operation canreduce latency and the overhead associated with synchronizing all of thenodes to ensure that nodes do not attempt to transmit when they shouldbe receiving a packet. Routing benefits created by full-duplex signalshaping can also be used to aggregate backhaul capacity (e.g., if onebackhaul link is overloaded, the node could act as a router and offloadthe data it cannot support onto a node which has excess backhaulcapacity).

Fall-duplex signal shaping can, in some exemplary embodiments, be usedin the context f peer-to-peer networks (e.g., WiFi Direct). Withoutfull-duplex operation, one node cannot transmit to another node if it isalready receiving from another node. Full-duplex signal shaping enablesdifferent peer-to-peer connections to operate independently and reducesthe overhead associated with sending out beacons to announceavailability to receive.

In some implementations, an advantage is that full-duplex signal shapingenables radios to cleanly separate the concern of utilizing fragmentedspectrum from the design of higher physical/media access control(“PHY/MAC”) layers. Existing methods for signal shaping (e.g.,discontiguous orthogonal frequency division multiplexing (“OMNI”)) donot allow for full-duplex and, as such, couple the usage of all spectrumfragments. By contrast, in some implementations of the system andmethods described herein, every single spectrum fragment can be used foreither transmit or receive.

Moreover, current methods and devices that enable full-duplex, filterthe self-interference rather than cancelling the self-interference.These filters are typically designed with fixed analog components andoperate over a pre-specified range of frequencies (e.g. notching out thetransmitted signal in a particular range of pre-determined frequencieswhile allowing the received signal to pass through a different range ofpre-determined frequencies). One of the advantages of the currentsubject matter system is that while different filter components arerequired to filter different frequency ranges, a single cancellationsystem can cancel the transmitted signal no matter what frequency rangesit is operating on. Thus, a single cancellation system could replaceseveral discrete filtering components and allow for operation that ismore flexible.

In some implementations, the current subject matter system can provideself- interference cancellation, as opposed to analog filtering, toenable simultaneous transmission and reception on different bands. Forexample, an analog self-interference cancellation might involve a singleantenna utilizing a circulator (or isolator) to separate out thetransmit and receive signals. It can also involve more than two antennas(e.g., 3 antennas, such as 2 transmit, 1 receive, and the 2 transmitantennas can be placed half of a wavelength apart from one another). Adifferent digital cancellation system can implement filters, such as forexample, Butterworth, Chebyshev, etc.

Many everyday devices, e.g., mobile phones, wireless local area networks(“LANs”), Bluetooth® enabled devices, ZigBee® small low-power digitalradios, global positioning systems (“GPS”), two-way radios such as LandMobile, FRS and GMRS radios, operate in a ultra-high frequencycommunication spectrum of 300-3000 MHz. Given the types of devices thatoperate in this band, this spectrum can become increasingly fragmented.The most common operational frequency for these devices is approximately2.4 GHz, where these devices operate in an Industrial, Scientific, andMedical (“ISM”) radio band (as established by first established at theInternational Telecommunications Conference of the InternationalTelecommunications Union in 1947) the unlicensed ISM band, it is notuncommon for users any multiple wireless devices (e.g., WiFi™ devices,Bluetooth® enabled devices, ZigBee® radios), where each device canoperate in its own contiguous narrow band of varying widths. This canlead to fragmentation of the 2.4 GHz ISM band into various chunks (e.g.,100 MHz chunks). Spectrum fragmentation can vary over time and space, asthe set of available ISM bands can depend on which devices are operatingat a particular location at any given time. FIG. 5 illustrates aplurality of devices that can share a wireless spectrum and can operateon different fragments. The devices can include Bluetooth enabled device502, a ZigBee® radio 504, and a WiFi™ device 506. Other devices canshare the wireless spectrum as well.

FIG. 1 illustrates an exemplary radio 100, such as a base station oraccess point, according to some implementations of the current subjectmatter. The radio 100 can include antenna(s) 108 configured to transmitvia a downlink and configured to receive via an uplink. The radio 100can include a radio interface 106 coupled to the antenna 108, and acontroller 104 for controlling the radio 100 and for accessing andexecuting program code stored in memory 102. The radio interface 106 caninclude other components, such as filters, converters (e.g.,digital-to-analog converters and the like), mappers, signal shapingcomponents, a Fast Fourier Transform (“FFT”) module, and the like, togenerate symbols for a transmission via one or more downlinks and toreceive symbols (e.g., via an uplink). In some implementations, theradio 100 can also be compatible with WiFi™, Bluetooth®, GSM EDGE RadioAccess Network (“GERAN”), Universal Terrestrial Radio Access Network(“UTRAN”), and Evolved Universal Terrestrial Radio Access Network(“E-UTRAN”), and/or other standards and specifications as well. Theradio 100 can be configured to perform one or more aspects of thesubject matter described herein.

FIG. 2 illustrates another exemplary radio 200, such as a userequipment, according to some implementations of the current subjectmatter. The radio 200 can include an antenna 208 for receiving signalson a downlink and transmitting signals via an uplink. The radio 200 canalso include a radio interface 206, which can include other components,such as filters, convene (e.g., digital-to-analog converters and thelike), symbol demappers, signal shaping components, an inverse FastFourier Transform (“WFT”) module, and the like, to process symbols, suchas Orthogonal Frequency-Division Multiple Access (“OFDMA”) symbols,carried by a downlink or an uplink. In some implementations, the radio200 can also be compatible with WiFi™, Bluetooth®, GERAN, UTRAN,E-UTRAN, and/or other standards and specifications as well. The radio200 can include at least one processor, such as processor 204, forcontrolling radio 200 and for accessing and executing program codestored in memory 202. The radio 200 can be configured to perform one orsnore aspects of the subject matter described herein.

Most conventional devices operate on contiguous spectrum bands and thus,are unable to take advantage of the fragmented spectrum. Someconventional devices include modified physical layers (“PHY”) and mediaaccess control (“MAC”) layers (also referred to as higher layers) sothat they can operate on the fragmented spectrum. Such modificationsinclude a wideband orthogonal frequency division multiplexing (“OFDM”)PHY layer that uses only subcarriers that are arc in the empty spectrumfragments and a modified MAC layer to ensure that all available spectrumfragments are utilized fully. However, because conventional radioscannot transmit and receive simultaneously over arbitrary differentbands, these devices cannot exploit fragmented spectrum without asignificant complexity and still provide suboptimal performance. Forexample, if a radio device decides to use even one fragment to transmiton, then its only choice if it wants to use any of the other fragmentsis to transmit there too and vice versa for receive. Consequently inorder to maximize spectrum utilization among a set of nodes competingfor fragmented spectrum, the MAC protocol has to dynamically estimatewhich node is sending to whom, and then coordinate nodes such that anytransmitting node does not have any transmission intended for it at thesame time, all while ensuring that all fragments are assigned for use.Inevitably, complexity of such distributed coordination grows, leadingto inefficient spectrum utilization.

Functionalities of a communications system are governed by the OpenSystems Interconnection (“OSI”) model (ISO/IEC 7498-1), wherebyfunctions of the communications system are grouped in terms ofabstraction layers. There are seven layers in the OSI model, whichinclude

-   -   a physical layer (“PHY”) that defines electrical and physical        specifications for devices (e.g., it defines the relationship        between a device and a transmission medium),    -   a data link layer that provides functional and procedural means        to transfer data between network entities and to detect and        correct errors that occur in the physical layer (e.g., it can        include the following functionalities/sub-layers: framing,        physical addressing, flow control, error control, access        control, and media access control (“MAC”)),    -   a network layer that provides functional and procedural means of        transferring variable length data sequences from a source host        on one network to a destination host on a different network        while maintaining the quality of service requested by the        transport layer,    -   a transport layer that provides transparent transfer of data        between end users, thereby providing reliable data transfer        services to the upper layers,    -   a session layer that controls connections between computers,        establishes, manages and terminates connections between local        and remote applications, provides for full-duplex half-duplex,        or simplex operation, and establishes checkpointing,        adjournment, termination, and restart procedures,    -   a presentation layer that establishes context between        application-lay entities, in which the higher-layer entities use        different syntax and semantics if the presentation service        provides a mapping between them, and    -   an application layer, which is the OSI layer closest to the end        user, whereby the OSI application layer and the user interact        directly with the software application.

FIG. 3 illustrates an exemplary implementation of the communicationsystem 300, according to some implementations of the current subjectmatter. The system 300 can include a plurality of devices havingrespective transmitting and receiving antennas 310 (as shown in FIG. 3,Tx stands for transmitting antennas and Rx stands for receivingantennas, where “1” designates device 1; “2” designates device 2, etc.).The antennas can communicate with MAC layer 502 and PHY layer 504. Thesystem 300 can also include a signal shaping layer 506 coupled to thelayers 502 and 504 and configured to provide process and provide signalsto the layers 502 and 504, as described below in connection with FIG. 4.

In some implementations, the current subject matter provides afull-duplex signal shaping capability to the higher layers (e.g., PHY,MAC, etc.) to use fragmented spectrum. A full-duplex signal shaping caninclude transmitting on an arbitrary set of spectrum fragments of thewireless spectrum and receiving on a different arbitrary set of spectrumfragments of the wireless spectrum. If necessary, the transmitting andreceiving can be performed simultaneously. Thus, the current subjectmatter system can decouple use of different spectrum fragments, insteadof having one complex wideband PHY and MAC protocol that operates overthe entire fragmented spectrum,the system can run several independent,contiguous narrowband PHY and MAC instances on each spectrum fragment.Hence, the current subject matter system's signal shaping can preservedesign modularity and enable reuse of higher layers of a communicationsystem.

In some implementations, the current subject matter relates to a systemand a method for providing high performance full-duplex signal shapingsignals in communication devices. An exemplary communication device caninclude a receiver circuitry that can receive signals transmitted byanother communication device, a transmitter circuitry that can transmitsignals for reception by another communication device, and variousprocessing circuitry that can process received signals, prepare signalsfor transmission, and/or perform various other functions. An exemplarycommunication device can include a mobile telephone, a Bluetooth®enabled device, a ZigBee® small low-power digital radio, a GPS device, atwo-way radio, such as Land Mobile, Family Radio Service (“FRS”) andGeneral Mobile Radio Service “GMRS”) radios, and/or any other devices.The current subject matter system can perform at least one of thefollowing functions: a full-duplex operation and a dynamic signalshaping. The following is a brief discussion of each of these functions.

In some implementations, during the full-duplex operation a signalshaping radio device can allow higher layers (e.g., PHY, MAC, etc.) ofthe communication device to simultaneously transmit and receive onarbitrary but different sets of spectrum fragments of the wirelessspectrum. The current subject matter system can resolve receiversaturation during such simultaneous receive/transmit operations.Receiver saturation refers to self-interference that saturates thereceive circuit's analog-to-digital converter circuitry and zeroes outthe received signal, during transmission by the transmitter circuitryeven if the reception is on a different band.

In some implementations, the current subject matter can include aprogrammable digital fitter to shaped signals in order to fit spectrumfragments that are available for the purposes of dynamic signal shapingfunctionality. This can account for the dynamic nature of the availablespectrum fragments as well as their ability to change over time.

In some implementations to enable full-duplex operation on separatebands, the current subject matter can include a self-interferencecancellation mechanism that can reduce an amount of self-interferenceand ensure that an analog-to-digital converter in the receive circuitry(as shown in FIG. 4 and discussed below) is not saturated. Theself-interference cancellation mechanism does not leak interference intoadjacent bands and does not hurt receive performance. It can include areconfigurable filter engine that can provide efficient and programmabledigital filtering, as discussed below with regard to FIG. 4.

FIG. 4 illustrates an exemplary full-duplex signal shaping system 400,according to some implementations of the current subject matter. Thesystem 400 can be implemented in a communications device, such as thosereferenced above. The system 400 can be implemented in a stand-alonedevice and/or a communications network.

The system 400 can include a self-interference cancellation component402 and a filter engine component 404. The system 400 can include areceiver antenna or component (“Rx”) 406 and a transmitter antenna orcomponent (“Tx”) 410. The components 402 and 404 can be part of theself-interference cancellation component 402 circuitry. The component402 can include a power splitter 408 that can include a high power portand a low power port, where the high power port of the power splitter408 can be coupled to the transmitter antenna 406 and the low power portcan be coupled to an attenuation and delay circuitry 412. The powersplitter 408 can be a passive device that can couple a defined amount ofthe electromagnetic power in a transmission line to a port enabling thesignal to be used in another circuit. The splitter 408 can couple powerflowing in one direction, whereby power entering the output port can becoupled to an isolated port but not to the coupled port. In an exemplaryembodiment, the power splitter 408 can be an 8 dB power splitter thatcan be used to obtain a reference signal and reduce the transmit powerby 8 dB. The circuitry 412 can be coupled to a balun transformercircuitry 414. A balun can be an electrical device that can convertbetween a balanced signal (two signals working against each other, whereground is irrelevant) and an unbalanced signal (a single signal workingagainst a ground or a pseudo-ground). A balun can take many forms andcan include devices that transform impedances but need not do so, wheretransformer baluns can be used to connect lines of differing impedance.In this case, the balun 414 can be used as a subtractor circuit, wherethe transmitted signal does not suffer a power loss (e.g., 3 dB powerloss). This is contrary to conventional systems, where baluns are usedas inverters, resulting in a power loss (e.g., 3 dB power loss). In theconventional systems, transmit antenna transmits a positive signal andto cancel self-interference, the radio combines a negative signal withits received signal after adjusting the delay and attenuation of thenegative signal to match the self-interference.

The filter engine 404 can programmable filtering elements 428 that caninclude various filtering structures 430 and intermediate frequencyconverters 432. The filter engine 404 can also include a filter engineapplication programming interface (“API”) 434.

The self-interference cancellation circuitry 402 can be coupled to thefilter engine 404 circuitry via at least one receive line 440 and atleast one transmit line 450. The receive line 440 can be coupled to thereceive antenna 410 via the balun transformer 414. It can process areceived radio frequency (“RF”) signal through a power source 418 thatconverts RF signal to a baseband signal. The baseband signal can befiltered through a low-pass filter 422 and passed onto ananalog-to-digital converter (“ADC”) 426. The ADC 426 can sample thereceived signal at a predetermined sampling frequency and pass it ontoto the fitter engine 404. The engine 404 can filter the signal andoutput it as digital baseband Rx signal to protocol layers. The transmitline 450 can be coupled to the transmit antenna 406 via the powersplitter 408 and can perform functions similar to those performed duringsignal processing on the receive line 440 but in a reverse order asfollows. The filter engine 404 can pass a filtered digital baseband Txsignal from protocol layers to a digital-to-analog converter (“DAC”)424. The DAC 424 can resample the signal and pass it to a low passfilter 420, which can apply it to a power source 416 to generate atransmission RIP signal from the baseband signal for transmission by thetransmit antenna 406.

In some implementations, the current subject matter system can achievefull-duplex operation over different but arbitrary spectrum fragments bycancelling self-interference in analog instead of filtering it. Theself-interference signal can be subtracted from the received signal sothat its effect is eliminated and receiver saturation does not occur.This can be accomplished by using the balun transformer 414. The currentsubject matter system can also determine how much cancellation is neededto ensure receiver saturation does not occur. The amount of cancellationneeded can be determined based on at least, the following two fact (1)dynamic range/resolution ADC 426; and (2) range of signal strengths thatare expected.

Dynamic range (“DR”) is defined as the ratio between largest andsmallest possible values of a variable of interest. At the transmitter,the dynamic range of the DAC can determine the maximum ratio between thepowers of the strongest and weakest transmissions. At the receiver, theADC's dynamic range can define the maximum ratio between the strongestand weakest received signal power. When the dynamic range is exceeded,the converter's quantization noise can bury he weaker signals. Thedynamic range of the ADC can be calculated through the followingformula:

DR (dB)=6.02×n+1.7 6dB   (1)

where a is the number of bits in the DAC/ADC resolution. Higher dynamicranges can equate with better performance. In some implementations, thecurrent subject matter system can use a 12-bit DAC/ADCs which canprovide about 74 dB of dynamic range.

At the transmitter, the maximum ratio between transmit powers overdifferent fragments will rarely exceed 30 dB so DAC dynamic range isusually not a concern. On the other hand, if the transmitter isoperating while the system attempts to receive,the dynamic range of theADC at the receiver can be critical because the transmitted signal canbe much stronger than the received signal. To determine the required ADCdynamic range, the range of expected signal strengths can be calculated.Assuming that the transmit and receive receive antennas are reasonablyseparated, the attenuation between the two due to path loss can becalculated as follows:

Path Loss(dB)=36.56+20 log₁₀(f)+20 log₁₀(d)   (2)

where f is the carrier frequency in MHz and d is the distance in miles.Assuming that the transmit and receive antennas are separated by 10 cm,the path loss between transmitter and receiver can be approximately 23dB which can be a maximum output from a WiFi 2.4 GHz antenna. Because atypical thermal noise-floor for WiFi systems is approximately −95 dBm,the power of the weakest decodable signal is −90 dBm (according to IEEE802.11 standard, the lowest signal-to-noise ratio is approximately 5dB).

Thus, the amplitude of the self-interference signal at the receiver is 0dBm. (assuming 23 dBm transmit power, the maximum in WiFi). Thus, ADC426 can require 90 dB (0-(-90)) in dynamic range in order tosimultaneously transmit and receive. In some implementations, the amountof cancellation required can increase as ADC resolution drops.

In some implementations, the current subject matter system'sself-interference cancellation mechanism can provide sufficientcancellation to ensure receive saturation does not take place, does notleak any interference to adjacent spectrum fragments, and does not causesignal power loss for the transmitted signal.

In some implementations, to avoid interference leakage, passivecomponents that do not introduce distortion can be used in the currentsubject matter system (such as the one shown in FIG. 4). The currentsubject matter system can provide for cancellation of a certain amountof signal power (e.g., 20-25 dB of cancellation compared to the 35 dBrequired for single-channel full-duplex). Hence, precise delay matchingwith the over-the-air transmitted signal may not be needed, an almostgood delay-match might suffice. Further, as stated above, baluntransformer can be used as a subtractor circuit, as shown in FIG 4. Thebalun transformer, in typical operation, can take an input signal on theunbalanced tap and produce two output signals which can be inverses ofeach other on the balanced taps. The same operation can be modeled inreverse as taking two inputs on the balanced side and producing thesubtraction of the input signals as the signal on the unbalanced side.Hence, if the two inputs are exact replicas of each other, the outputwill be a zero signal.

In some implementations, the self-interference cancellation can preventthe receiver ADC from saturating, but by itself, it can be insufficientto fully cancel out the interference between bands. However, with theADC dynamic range no longer saturated, the current subject matter systemcan utilize programmable digital filters of the filter engine 404 shownin FIG. 4 to digitally remove the remaining self interference from thereceived signal for programmatically shaping the signal at the transmitand receive antennas.

The filter engine 404 can ensure that the transmitted and/or receivedsignals are shaped according to the higher layer specification of whichspectrum fragments to use. At the receiver side, the sampled widebandsignal can be converted into narrowband streams by down-converting andfiltering to remove adjacent band interference. The reversefunctionality can be performed at the transmitter side, where narrowbandbaseband streams can be up-converted and filtered to prevent aliasing(i.e., an effect that causes different signals to becomeindistinguishable (or aliases of one another) when sampled.

The filter engine 404 can include the ADC 426 and DAC 424, both of whichcan be capable of operating at a predetermined. Nyquist rate (e.g.,which can be the required Nyquist rate to create signals that span theentire 100 MHz ISM band). Further, on the analog RF side, there is asingle oscillator at 2.45 GHz which can up-convert the shaped signal tothe ISM band. The filter engine 404 can perform the following tasks toshape the signals for transmission: resampling, filtering, and mappingof signal streams.

For resampling, since the DAC 424 expects an input signal at thepredetermined. Nyquist rate (e.g., 200 MS/s), the digital basebandtransmission streams 436 can he up-sampled (e.g., 40 Msamples/secstreams can be up-sampled to 200 Msamples/sec). To accomplish this, theup-sampler can interpolate (i.e., insert extra samples) to reach thepredetermined. Nyquist rate (e.g., 200 MS/s).

For filtering, the filter engine can low-pass filter both up-sampledstreams to remove any undesirable aliasing effects generated by theresampling and retain only the up-sampled-baseband version of eachstream.

Subsequent to resampling and filtering, the filter engine can perform amapping operation. For mapping, the filter engine 404 can process two200 MS/s streams each occupying 20 MHz at a center frequency. The filterengine 404 can move the 20 MHz frequencies to the specified fragments inthe 100 MHz band, i.e., to −38 MHz and 22 MHz, respectively(corresponding to 2.412 GHz and 2.472 GHz at a center frequency of 2.45GHz). The signal streams can be added together and sent to the DAC 424.After that, the signal streams can be up-converted to the carrierfrequency of 2.45 GHz and transmitted over the air.

As stated above, the filter engine 404 can include filter structures430, intermediate frequency converters 432, and filter engineapplication programming interface (“API”) 434. The filter structures 430can include a collection of configurable programmable filters. Thefilters can include at least one of the following: a finite impulseresponse (“FIR”) filter (which is a filter whose impulse response (orresponse to any finite length input) is of finite duration and settlesto zero in finite time), an infinite impulse response (“HR”) filter(which is a filter that has an impulse response function that isnon-zero over an infinite length of time), a resampling filter, and/orany other filters. The filters in the filter structures 430 can beconfigured and sequenced to provide resampling and filteringfunctionalities discussed above.

The intermediate frequency converters 432 can nap the signal from anincoming digital baseband 436 to a digital intermediate frequency(“IF”), and provide mapping functionality.

The filter engine API 434 can act as a substrate that can allowprogrammable interconnection of the filter structures 430 and IFconverter 432 to obtain the desired signal shaping. The. API 434 canconfigure the filters, up/down samplers, and digitalup-/down-converters. It can also coordinate movement of signal streamsacross these elements. It can collect all of the input signal streams436, add them, and send the final stream to the DAC 424. The analogoutput of the DAC 424 can be upconverted to a 2.45 GHz signal frequencyand transmitted by the transmission antenna 406. For the receivingshaped signals, the API 434 can perform the above process but in areverse manner. Thus, by performing the above operations, the currentsubject matter system's self-interference cancellation component 402 andthe filtering engine component 404 can perform full-duplex signalshaping.

FIG. 6 illustrates an exemplary method 600 for performing a full-duplexsignal shaping that can be performed by the system 400 (shown in FIG.4), according to some implementations of the current subject matter. Asstated above, the system that can perform the method 600 can include thetransmitting antenna 406 for transmitting a signal over a plurality ofwireless spectrum fragments, the receiving antenna 410 for receiving asignal from the plurality of wireless spectrum fragments, and the signalprocessing layer 306 (as shown in FIG. 3) in communication with thetransmitting and receiving antennas. The system can be used forsimultaneously causing reception of the received signal and transmissionof the transmitted signal.

At 602, a portion of interference from the received signal can beremoved or cancelled. The interference can be caused by the transmittedsignal and affect the received signal. It can be cancelled using theinterference cancellation component 402 (shown in FIG. 4) of the signalprocessing layer. As discussed above, the interference cancellationcomponent can include a balun transformer that can subtract a certainamount of power for the signal to reduce interference. The amount ofpower to be deducted can be determined based on a variouscharacteristics associated with the system as well as thereceived/transmitted signals.

At 604, a remaining portion of the interfence can be removed from thereceived signal. This can be accomplished using the filtering componentor filter engine 404 (shown in FIG. 4) of the signal processing layer.

In some implementations, the portion of the interference to be cancelledby the interference cancellation component can equal to a predeterminedamount of power to be removed from the received signal. Thepredetermined amount of power can be determined based on at least one ofthe following: dynamic range of at least one of the received andtransmitted signals, and a range of expected signal strength. Thedynamic range of the received signal can be determined based on a ratioof powers of a strongest received signal and a weakest received signal.The dynamic range of the transmitted signal can be determined based on aratio of powers of a strongest transmitted signal and a weakesttransmitted signal. The range of expected signal strength can bedetermined based on a distance separating the transmitting antenna and areceiving antenna.

In some implementations, the interference cancellation component caninclude a balanced-unbalanced transformer component for subtracting thepredetermined amount of power from the received signal. The interferencecancellation component can include at least one passive electroniccomponent.

In some implementations, the filtering component can include a receivercircuitry for performing at least one of the following operationssampling of the received signal, down-converting the sampled receivedsignal into a narrowband stream, and filtering the down-converted signalto remove the second portion of the interference. The filteringcomponent can also include a transmitter circuitry for performing atleast one of the following operations up-converting of the transmittedsignal and filtering the up-converted signal to prevent aliasing of thetransmitted signal with at least another signal Further, the filteringcomponent can include a plurality of filters arranged in a sequence forperforming sampling and filtering of the received signal processed bythe interference cancellation component to remove the second portion ofthe interference. The plurality of filters can include at least oneprogrammable filter, which includes at least one of the following: afinite impulse response filter, an infinite impulse response filter, anda resampling filter.

In some implementations, the filtering component can perform mapping ofat least one signal received from at least one communication protocollayer to at least one frequency fragment in a wireless frequency bandfor transmission by the transmitting antenna.

The received signal and the transmitted signal can be in the wirelessfrequency band.

The following is a brief discussion of an exemplary experimentalimplementation of the current subject matter system 400. The belowdiscussion is not to be construed as limiting the scope of the currentsubject matter system and/or any of its components in any way. It isprovided here for purely illustrative purposes.

Exemplary Experimental Implementation

The current subject matter system 400 was experimentally implementedusing a Virtex-5 LX30 field-programmable gate array (“FPGA”) (which isan integrated circuit designed to be configured by a customer aftermanufacturing) based software radios available from National InstrumentsCorporation, Austin, Tex., USA. The FPGA used had a total of 19,200basic LUT-FF and 32 DSP48E arithmetic unit resources. The FPGS wasconnected to an NI5781 baseband transceiver (also available fromNational Instruments Corporation, Austin, Tex., USA), which served asboth the ADC and the DAC. The NI5781 was operated at 100 MS/s for boththe in-phase and quadrature components, allowing the current subjectmatter system to cover approximately 100 MHz of total bandwidth andprovide signal shaping over almost the entire 2.4 GHz ISM band. TheNI5781 baseband transceiver included quadrature 100 MS/s 12-bit ADCs and100 MS/s 16-bit DACs and provided approximately 86 dB of dynamic rangeat the receiver. The converter was attached to the interposer boardthrough differential connections, which formatted the signals for theXCVR2540 high-performance transceiver operating in the 2.4 GHz range(also available from National Instruments Corporation, Austin, Tex.,USA).

The XCVR2450 performed the analog down conversion to baseband and thebandwidth and receiver gain were controllable from the NI PXIe-8133 RTModule (also available from National Instruments Corporation, Austin,Tex., USA). Because the XCV2450 operated in the ISM band, there wereseveral sources of external interference which came from devices such asWiFi, Bluetooth, wireless devices, etc.

The experimental system was connected to the two XCVR2450 daughtercards, with the received signal wires connecting to one card and thetransmit signal wires connecting to the other. The signal from thetransmit daughter card was first passed through an 8 dB power splitterand the high power port output was fed to the transmitter antenna. Thelower power port output eras fed into a programmable attenuator line,which was then connected to one end of the balanced tap of the balun.The signal from the received antenna was directly connected to the otherbalanced tap and the unbalanced output of the balun, which was thesubtraction of the two input signals, was connected to the receiverdaughter card. The two antennas, one for transmit and one for receive,were placed within 10 cm of one another.

A programmable attenuator of the experimental system's self-interferencecancellation block was tuned once, for a particular transmit power andlocation of the node. After, the block was static, thereby making it apassive component. While channel fluctuations caused the amount ofself-interference to vary slightly, the mean cancellation was determinedto be around 25 dB. Because the experimental system's self-interferencecancellation component did not require an active component, it providedflat cancellation.

The filter engine hardware used in the experimental system included anNI PXIe-7695 FPGA and a real-time processor NI PXIe-8133 RT Module (alsoavailable from National Instruments Corporation, Austin, Tex., USA). TheFPGA was directly connected to the ADC/DAC (NI 5781 Adapter Module) andreceived baseband sample at a rate of 100 complex MS/s. The FPGA wasthen connected to the real-tune processor, which controlled the FPGAresources via the filter engine API.

The FPGA was a Virtex-5 95T, with 14,720 slices and nearly 9 Mb ofrandom access memory (“RAM”). The slices were used for almost everyoperation on the FPGA, while the RAM use was limited to storing datawhile averaging and providing temporary storage when restructuring theoutput of the definition of FFTs from bit order to natural order. Forthe filter structures, DSP48E slices available on the Xilinx LX30 wereutilized. Each of these slices is a highly configurable arithmetic logicunit which feature pipelined multiplier, adder and accumulator stagesand can he clocked at up to 550 MHz. Slices can be individuallyprogrammed and/or cascaded to implement FIR, IIR, and resamplingfiltering with relative case.

The IF converters were implemented using the standard CoordinateRotation Digital Computer (“CORDIC”) algorithm, which is an algorithm tocalculate hyperbolic and trigonometric functions, and a complexmultiplier. In total, each IF converter requires approximately 1100LUT-FF resources and 3 DSP48E slices, and can be clocked at up to 300MHz. Based upon stream requirements, both the CORDICs and DSP48E slicescan be time-division multiplexed to support multiple streams. Theexperimental system had 10 filter structures (10 DSP48E slices) and 3 IFconverters (9 DSP48E slices and 3300 LUT-FFs). Thus, the overallresource consumption on an off-the-shelf, mid-range FPGA was around 15%of the hardware resources.

The NI PXIe-8133 RT Module operates with four 1.733-GHz cores, whichwere capable of dynamically splitting tasks between two threads each,giving the RT module a total of 8 processing threads. These threads wereutilized to implement the filter engine API, channel estimation,frequency offset information, and symbol decoding. The filter engine APIalso specifying which fragments to transmit and receive over along withthe desired bandwidths of each fragment. The filter engine thenconfigured the filter structures, IF converters, and fractionalresamplers to fit the user specifications.

In the experimental system, a WiFi style OFDM PHY and a carrier sensemultiple access (“CSMA”) MAC on the realtime operating system (“OS”)were implemented. The OFDM PHY was configured to operate over differentbandwidths (from 20 MHz to 5 MHz), and ran in realtime on the SDRplatform. It supported all WiFi constellations (from BPSK to 64-QAM) aswell as channel coding rates (½, ⅔, ¾ convolutional coding).

During experimental operation, the above experimental system achievedmore than 24 dBm self-interference cancellation. The system achieved thesame throughput over multiple links as multiple independent radiodevices receiving multiple signal streams. Further, as compared toconventional active cancellation systems that introduce sideband leakagethereby reducing system throughput, the experimental system producednear optimal throughput.

In some implementations, the current subject matter system can beimplemented in access point networks, cellular networks, WiFi directnetworks, and/or any other networks.

In access point networks, signals can be shaped to avoid interferencesand latency for multiple clients can be appropriately mitigated. Thecurrent subject matter system can provide nearly three times throughputincrease. The current subject matter system can improve throughputbecause the PHY/MAC instance on each spectrum fragment can be decoupledfrom the others. In the current subject matter system, each spectrumfragment behaves as if it is an independent WiFi network and no clienthas to be blocked because a client on some other spectrum fragment isbeing serviced. Thus, the current subject matter system can improveoverall spectrum utilization and network throughput. The current subjectmatter system further can improve latency and provide a better qualityof service.

In the WiFi-Direct (“WD”) networks that are used for peer-to-peerconnectivity between gadgets, the current subject matter system canenable a device to connect to an access point and to the WD peer onseparate spectrum fragments and completely decouple their operation. Thedevice can be transmitting, receiving or both on any combination of thetwo networks, it does not have to worry about synchronized scheduling,thereby simplifying the design of the WD networks.

The subject matter described herein may be embodied in systems,apparatus, methods, and/or articles depending on the desiredconfiguration. In particular, various implementations of the subjectmatter described herein may be realized in digital electronic circuitryintegrated circuit specially designed ASICs (application specificintegrated circuits), computer hardware, firmware, software, and/orcombinations thereof. These various implementations may includeimplementation in one or more computer programs that are executableand/or interpretable on a programmable system including at least oneprogrammable processor, which may be special or general purpose, coupledto receive data and instructions from, and to transmit data andinstructions to, a storage system, at least one input device, and atleast one output device.

These computer programs (also known as programs, software, softwareapplications, applications, components, or code) include machineinstructions for a programmable processor, and may be implemented in ahigh-level procedural and/or object-oriented programming language,and/or in assembly/machine language. As used herein, the term“machine-readable medium” refers to any computer program product,apparatus and/or device (e.g., magnetic discs, optical disks, memory,Programmable Logic Devices (PLDs)) used to provide machine instructionsand/or data to a programmable processor, including a machine-readablemedium that receives machine instructions as a machine-readable signal.

Similarly, systems are also described herein that may include aprocessor and a memory coupled to the processor. The memory may includeone or more programs that cause the processor to perform one or more ofthe operations described herein.

Although a few variations have been described in detail above, othermodifications or additions are possible. In particular, further featuresand/or variations may be provided in addition to those set forth herein.For example, the implementations described above may be directed tovarious combinations and subcombinations of the disclosed featuresand/or combinations and subcombinations of several further featuresdisclosed above. In addition, the logic flow depicted in theaccompanying figures and/or described herein does not require theparticular order shown, or sequential order, to achieve desirableresults. Other embodiments may be within the scope of the followingclaims.

The systems and methods disclosed herein can be embodied in variousforms including, for example, a data processor, such as a computer thatalso includes a database, digital electronic circuitry, firmware,software, or in combinations of them. Moreover, the above-noted featuresand other aspects and principles of the present disclosedimplementations can be implemented in various environments. Suchenvironments and related applications can be specially constructed forperforming the various processes and operations according to thedisclosed implementations or they can include a general-purpose computeror computing platform selectively activated or reconfigured by code toprovide the necessary functionality. The processes disclosed herein arenot inherently related to any particular computer, network,architecture, environment, or other apparatus, and can be implemented bya suitable combination of hardware, software, and/or firmware. Forexample, various general-purpose machines can be used with programswritten in accordance with teachings of the disclosed implementations,or it can be more convenient to construct a specialized apparatus orsystem to perform the required methods and techniques.

As used herein, the term “user” can refer to any entity including aperson or a computer.

Although ordinal numbers such as first, second, and the like can, insome situations, relate to an order; as used in this document ordinalnumbers do not necessarily imply an order. For example, ordinal numberscan be merely used to distinguish one item from another. For example, todistinguish a first event from a second event, but need not imply anychronological ordering or a fixed reference system (such that a firstevent in one paragraph of the description can be different from a firstevent in another paragraph of the description).

The foregoing description is intended to illustrate but not to limit thescope of the invention, which is defined by the scope of the appendedclaims. Other implementations are within the scope of the followingclaims.

To provide for interaction with a user, the subject matter describedherein can be implemented on a computer having a display device, such asfor example a cathode ray tube (CRT) or a liquid crystal display (LCD)monitor for displaying information to the user and a keyboard and, apointing device, such as for example a mouse or a trackball, by whichthe user can provide input to the computer. Other kinds of devices canbe used to provide for interaction with a user as well. For example,feedback provided to the user can be any form of sensory feedback, suchas for example visual feedback, auditory feedback, or tactile feedback;and input from the user can be received in any form, including, but notlimited to, acoustic, speech, or tactile input.

The implementations set forth in the foregoing description do notrepresent all implementations consistent with the subject matterdescribed herein. Instead, they are merely some examples consistent withaspects related to the described subject matter. Although a fewvariations have been described in detail above, other modifications oradditions are possible. In particular, further features and/orvariations can be provided in addition to those set forth herein. Forexample, the implementations described above can be directed to variouscombinations and sub-combinations of the disclosed features and/orcombinations and sub-combinations of several further features disclosedabove. In addition, the logic flows depicted in the accompanying figuresand/or described herein do not necessarily require the particular ordershown, or sequential order, to achieve desirable results. Otherimplementations can be within the scope of the following claims.

What is claimed:
 1. A system for processing signals, comprising atransmitting antenna for transmitting a signal over a plurality ofwireless spectrum fragments; a receiving antenna for receiving a signalfrom the plurality of wireless spectrum fragments; and a signalprocessing layer in communication with the transmitting and receivingantennas for simultaneously causing reception of the received signal andtransmission of the transmitted signal, the signal processing layerincluding an interference cancellation component for removing a firstportion of interference from the received signal, wherein theinterference being caused by the transmitted signal and affecting thereceived signal; and a filtering component for removing a second portionof the interference from the received signal.
 2. The system according toclaim 1, wherein the portion of interference to be removed by theinterference cancellation component equals to a predetermined amount ofpower to be removed from the received signal.
 3. The system according toclaim 2, wherein the predetermined amount of power is determined basedon at least one of the following: dynamic range of at least one of thereceived and transmitted signals, and a range of expected signalstrength; the dynamic range of the received signal is determined basedon a ratio of powers of a strongest received signal and a weakestreceived signal; the dynamic range of the transmitted signal isdetermined based on a ratio of powers of a strongest transmitted signaland a weakest transmitted signal; the range of expected signal strengthis determined based on a distance separating the transmitting antennaand a receiving antenna.
 4. The system according to claim 3, wherein theinterference cancellation component includes a balanced-unbalancedtransformer component for subtracting the predetermined amount of powerfrom the received signal.
 5. The system according to claim 1, whereinthe interference cancellation component includes at least one passiveelectronic component.
 6. The system according to claim 1, wherein thefiltering component includes a receiver circuitry for performing atleast one of the following operations sampling of the received signal;down-converting the sampled received signal into a narrowband stream;and filtering the down-converted signal to remove the second portion ofthe interference.
 7. The system according to claim 1, wherein thefiltering component includes a transmitter circuitry for performing atleast one of the following operations up-converting of the transmittedsignal; and filtering the up-converted signal to prevent aliasing of thetransmitted signal with at least another signal.
 8. The system accordingto claim 1, wherein the filtering component includes a plurality offilters arranged in a sequence for performing sampling and filtering ofthe received signal processed by the interference cancellation componentto remove the second portion of the interference.
 9. The systemaccording to claim 8, wherein the plurality of filters include at leastone programmable filter, which includes at least one of the following: afinite impulse response filter, an infinite impulse response filter, anda resampling filter.
 10. The system according to claim 1, wherein thefiltering component performs mapping of at least one signal receivedfrom at least one communication protocol layer to at least one frequencyfragment in a wireless frequency band for transmission by thetransmitting antenna.
 11. The system according to claim 1, wherein thereceived signal and the transmitted signal are in the wireless frequencyband.
 12. A method for processing of signals using a system having atransmitting antenna for transmitting a signal over a plurality ofwireless spectrum fragments, a receiving antenna for receiving a signalfrom the plurality of wireless spectrum fragments, and a signalprocessing layer in communication with the transmitting and receivingantennas for simultaneously causing reception of the received signal andtransmission of the transmitted signal, the method comprising: removing,using an interference cancellation component of the signal processinglayer, a first portion of interference from the received signal, whereinthe interference being caused by the transmitted signal and affectingthe received signal; and removing, using a filtering component of thesignal processing layer, a second portion of the interference from thereceived signal.
 13. The method according to claim 12, wherein theportion of interference to be removed by the interference cancellationcomponent equals to a predetermined amount of power to be removed fromthe received signal.
 14. The method according to claim 13, wherein thepredetermined amount of power is determined based on at least one of thefollowing: dynamic range of at least one of the received and transmittedsignals, and a range of expected signal strength; the dynamic range ofthe received signal is determined based on a ratio of powers of astrongest received signal and a weakest received signal; the dynamicrange of the transmitted signal is determined based on a ratio of powersof a strongest transmitted signal and a weakest transmitted signal; therange of expected signal strength is determined based on a distanceseparating the transmitting antenna and a receiving antenna.
 15. Themethod according to claim 14, wherein the interference cancellationcomponent includes a balanced-unbalanced transformer component forsubtracting the predetermined amount of power from the received signal.16. The method according to claim 12, wherein the interferencecancellation component includes at least one passive electroniccomponent.
 17. The method according to claim 12, wherein the filteringcomponent includes a receiver circuitry for performing at least one ofthe following operations sampling of the received signal;down-converting the sampled received signal into a narrowband stream;and filtering the down-converted signal to remove the second portion ofthe interference.
 18. The method according to claim 12, wherein thefiltering component includes a transmitter circuitry for performing atleast one of the following operations up-converting of the transmittedsignal; and filtering the up-converted signal to prevent aliasing of thetransmitted signal with at least another signal.
 19. The methodaccording to claim 12, wherein the filtering component includes aplurality of filters arranged in a sequence for performing sampling andfiltering of the received signal processed by the interferencecancellation component to remove the second portion of the interference.20. The method according to claim 19, wherein the plurality of filtersinclude at least one programmable filter, which includes at least one ofthe following: a finite impulse response filter, an infinite impulseresponse filter, and a resampling filter.
 21. The method according toclaim 12, wherein the filtering component performs mapping of at leastone signal received from at least one communication protocol layer to atleast one frequency fragment in a wireless frequency band fortransmission by the transmitting antenna.
 22. The method according toclaim 12, wherein the received signal and the transmitted signal are inthe wireless frequency band.